Drawback mechanism for presses.



No. 897,048. PATENTED AUG. 25, 1908.

W. ASTFALGK. DRAWBAGK MECHANISM FOR PRESSES.

APPLICATION FILED JAN. 2, 1908..

liIlllHl UNITED STATES PATENT OFFICE.

DRAWBACK ILECHANISM FOR PRESSES.

Specification of Letters Patent.

Patented Aug. 25, 1908.

Application filed January 2, 1908. Serial No. 408,894.

To all whom it may concern:

Be it known that I, WILAND ASTFALCK, engineer, a subject of the GermanEmperor, and resident of N o. 21 Schlossstrassc, Tegel, near Berlin,Germany, have invented certain new and useful Improvements in Drawbackcomes more or less jammed in the work, and

penditure of force the work in the matrix or lower die, so that forwithdrawing it force is required to overcome the frictional resistance.If a withdrawing device is used capable of overcoming not only theweight and inertia of the moving parts, but also-the resistance due tothe jamming of the tool and work, the device is unwieldy and re uires anunnecessary exfor its actuation after the tool has been removed from thework. For efficient and economical working it is therefore necessary toprovide separate means for overcoming, with the least possibleexpenditure of force, the entirely independent resistances encountered.The present invention efiects this by providing that during thepenetration of the tool into or through the work, an auxiliary piston orpistons, independent from the withdrawing mechanism which overcomes theweight and inertia of the moving parts, is or are automatically broughtinto working position, so that when the main hydraulic cylinder isplaced in communication with the discharge conduit, the auxiliary pistonor pistons is or are hydraulically actuated for separating the tool fromthe work.

The stroke of the auxiliary piston or pistons is only of such amplitudeas to effect 0. assist in effecting, the separation of the tool from thework; after this separation the ordinary withdrawing mechanism acts onthe tool and main press-piston alone.

The annexed drawing illustratesby way of example a vertical, downwardlyacting press provided with the auxiliary withdrawing mechanism. Thepress is shown partly in section and partly in elevation, with thepress-piston in two different ositions.

a is the main press-cylim er, I) the presspiston and c the upper die,the parts I) and 0 being guided by means of the cross-head d and pillarse. The ordinary withdrawing mechanism consists of the hydraulic cylinderf and piston g, the latter being connected to the cross-head d by rodsh.

i is the lower die or matrix and 7c the work.

At the sides of the press are arranged auxiliary cylinders m containingpistons n the rods 0 of which extend so far upwards that the cross-headd comes into contact therewith as soon as the die 0 begins to penetrateinto the matrix with the work. The space above the piston in eachcylinder m communicates by a pipe 1" with the main cylinder a, and thespace below the piston communicates by a pipe 8 with a high-pressureaccumulator or mam.

The action of the press is as follows: It will be assumed that a dish orpot is to be made out of the plate 7c laced on the matrix i. The ipe acommunlcating with the cylinder f is p aced in communication with adischarge conduit and the pipe as is placed in communication with anaccumulator or a low-pressure pipe. Any suitable known mechanism may eused for controllin the respective valves in the manner required. Whenthe said connections have been made the parts I), d and c descend, asshown at the right hand side of the drawing, and the cross-head abutsagainst the piston rods 0 either at the moment at which the die 0 beginsto swage the plate is, or at a slightly later stage, as required. Theposition at which this abutment takes place depends on the height of thematrix and'the nature of the work, so that rods 0 may in some cases betoo short or too long. The said rods are, therefore, preferably providedwith exchangeable end pieces 0 of varying lengths. The press-cylinderhaving become filled to the extent corresponding to this position, thepipe x is placed in communication with the high-pressure conduit, sothat water under high pressure enters the cylinder a and forces the diea into the matrix. Water under high pressure then flows from thecylinder a into the cylinders m and acts on the pistons n from above, sothat the one-sided pressure on the said pistons from below isneutralized and the pistons can be easily moved to their lowerpositions. The length of the downward movement of the pistons n is equalto or smaller than the eil'eetive working stroke of the main piston b.When the swaging operation is completed the pipe u is connected to thehigh-pressure pipe, and the pipe at to the discharge-pipe. The waterabove the pistons n is thus discharged and the said pistons are liftedby the water acting on their undersurl'aces. The die 0 is thus liftedback to the position shown at the right-hand side of the Theconstruction of the press itself and thelocation of the auxiliarymechanism m n 0 are immaterial to the invention.

What I claim as my invention and desire to secure by United StatesLetters Patent 1. In a hydraulic press, the combination with the presscylinder, and the press piston, of a air of independent drawbackmechanisms or the press piston; one of said mechanismsbeing adapted toact on the piston during the first part of the return stroke of thepiston and the other mechanism being ada ted to act on the iston duringthe remain er of the return stroke of the piston. 2. In a hydraulicpress, the combination with the press cylinder and the press piston, ofa pair of independent drawback mechanisms for the press piston; one ofsaid mechanisms being adapted to act on the piston during the entirereturn stroke of the iston and the other mechanism being adapte to acton the piston during the first part only of the return stroke of thepiston.

3. In a hydraulic press, the combination with the press cylinder, thepress piston and the tool connected to the air of independent draw ackmechanisms or the press piston, c -acting during a part ress plston, ofa of the return stroke of the press piston to withdraw the tool from thework.

4. In a hydraulic press, the combination with the press cylinder, thepress piston and the tool connected to the press piston, of a drawbackmechanism for the press piston, an auxiliary drawback mechanism for thepress piston, means whereby said auxiliary mechanism is subjected toconstant ressurc in the direction of the return stroke 0 the presspiston, and means whereby the auxiliary mechanism is subjected to agreater pressure in the opposite direction during the working stroke of'the press-piston to cause the auxiliary mechamsm to move into itseffective position, whereby, when the last-named pressure is relieved,the pressure acting on the auxiliary mechanism in the direction of thereturn stroke of the press iston causes the auxiliary mechanism to witdraw the tool from the work.

5. In a hydraulic press, the combination with the press cylinder, thepress piston having a crosshead and the tool carried by the presspiston, of a drawback mechanism for the press piston, an auxiliarydrawback mechanism for the press piston comprising a cylinder, a pistonoperating in said cylinder and having a piston rod projecting outside ofthe cylinder and adapted for engagement with the cross-head of thepress-piston, a high pressure conduit in continuous communication withthe lower end of the auxiliary cylinder to hold the auxiliary piston inits uppermost position, and a conduit providing communication betweenthe press cylinder and the up er part of the auxiliary cylinder to causet e high pressure in the press cylinder to move the auxiliary piston andits piston rod into their lowermost position during the working strokeof the press piston, whereby, when the high pressure in the presscylinder is relieved the pressure acting on the under side of theauxihary piston causes the auxiliary piston and its piston rod to moveupwardly to withdraw the tool from the work.

The foregoing s ecification signed at Berlin this 17th day of December,1907.

. H WILAND ASTFALCK.

In presence of WOLDEMAR HAUPT, HENRY HAsrER.

